1. Field of the Invention
The present invention relates to an engine generator. In particular, the present invention relates to an improvement of an engine generator in which an engine and a generator are housed in a soundproofing case. The engine includes a crankshaft, an engine-side cooling fan fixed to the crankshaft, and an engine-side inlet provided at one end, in the axial direction, of the crankshaft for guiding cooling air to the engine-side cooling fan. The generator includes a rotating shaft connected at one end to the other end of the crankshaft, a generator-side cooling fan fixed to the rotating shaft, and a generator-side inlet provided at the other end, in the axial direction, of the rotating shaft for guiding cooling air to the generator-side cooling fan.
2. Description of the Related Art
Engine-driven generators are typically used as a power source for work performed outdoors such as, for example, on construction sites. Furthermore, many generators are completely covered with a soundproofing case so as to minimize operating noise in consideration of the operational and surrounding environments when performing work at night in an urban area. In engine generators with such a soundproofing case, the number of intake and exhaust openings is decreased and the size of the intake and exhaust openings is reduced in the pursuit of achieving operational silence. However, since the overall size of the openings is small, adequate consideration to cooling the interior of the soundproofing case must be taken.
From such a viewpoint, an engine generator disclosed in Japanese Utility Model Registration Publication No. 1-3777 includes, within a soundproofing case, a duct covering an engine cylinder head and an exhaust muffler, wherein cooling air is forcibly driven into the duct by a cooling fan, thereby cooling the engine and the exhaust muffler and eliminating thermal effects on other components of the generator.
Furthermore, an engine generator disclosed in Japanese Patent Application Laid-open No. 11-62607 has a dual structure in which a duct covering an engine, a generator, and an exhaust muffler is arranged within a soundproofing case, and cooling air is forcibly driven into the duct, thereby cooling a high temperature section and eliminating thermal effects on other components of the generator.
However, in the arrangement disclosed in Japanese Utility Model Registration Publication No. 1-3777, since outer shells of the engine and the generator are exposed within the soundproofing case, there is a possibility that, depending on the arrangement of internal components, heat released from the outer shells of the engine and the generator might be retained within the soundproofing case. Moreover, in the arrangement disclosed in Japanese Patent Application Laid-open No. 11-62607, the structure for forming a passage for the cooling air is complicated, and during maintenance it is necessary to remove and install the duct in addition to removing and installing the soundproofing case, which is troublesome, requires additional time, and increases overall maintenance costs.
It is an object of the present invention to overcome the deficiencies of the above-discussed related art. It is also an object of the present invention to provide an engine generator that enables an engine and a generator to be cooled by means of a simple structure and for which maintenance operations are easily carried out.
In order to accomplish the above-mentioned objects, the engine generator of the present invention includes an engine, a generator, and a soundproofing case housing the engine and the generator. The engine includes a crankshaft, an engine-side cooling fan fixed to the crankshaft, and an engine-side inlet at one end, in the axial direction, of the crankshaft, the engine-side inlet guiding cooling air to the engine-side cooling fan. The generator includes a rotating shaft coaxially connected at one end to the other end of the crankshaft, a generator-side cooling fan fixed to the rotating shaft, and a generator-side inlet at the other end, in the axial direction, of the rotating shaft, the generator-side inlet guiding cooling air to the generator-side cooling fan.
The engine generator further includes an engine-side partition fixedly disposed within the soundproofing case and defining a chamber to be cooled that houses sections of the engine and the generator that are to be cooled, and an engine-side air intake chamber that the engine-side inlet faces. The engine generator also includes a generator-side partition fixedly disposed within the soundproofing case so as to define the chamber to be cooled and a generator-side air intake chamber that the generator-side inlet faces. The soundproofing case includes a cover part covering the engine and the generator. The outer peripheries of the engine-side and generator-side partitions are in intimate contact with the inside face of the cover part. An exhaust vent is provided in an area of the cover part corresponding to the chamber to be cooled.
In accordance with the above-described structural arrangement, since the cover part, which is a component of the soundproofing case, is arranged so as to cover the engine and the generator, spaces defined by the engine-side and generator-side partitions are formed within the soundproofing case. A cooling air passage of the engine is used as a passage connecting opposite sides of the engine-side partition. A cooling air passage of the generator can also be used as a passage connecting opposite sides of the generator-side partition. Thus, cooling air is forced to flow so as to be combined in the chamber to be cooled where the sections to be cooled of the engine and the generator are housed, and then discharged to the outside from the exhaust vent, thereby forming the passages for cooling air within the soundproofing case with a simple structure while allowing maintenance to be carried out easily.
In addition to the above-described structural arrangement, the engine generator can also include an exhaust muffler, an air cleaner, a carburetor, and an electrical component. Additionally, the soundproofing case may include first and second side plates facing the outside faces of the engine-side and generator-side partitions with a gap therebetween. The exhaust muffler and the majority of the engine and the generator are housed in the chamber to be cooled. The air cleaner and the carburetor are housed in the engine-side air intake chamber formed within the soundproofing case between the engine-side partition and the first side plate. The electrical component is housed in the generator-side air intake chamber formed within the soundproofing case between the generator-side partition and the second side plate.
Accordingly, the soundproofing case is easily divided into the chamber to be cooled having a high temperature, which is in the middle, and air intake chambers having a low temperature on opposite sides of the chamber to be cooled, so that the arrangement of components can be appropriately achieved for the respective chambers to be effectively cooled.
The engine generator may further include an elastic seal provided between the engine-side partition and the engine, and an elastic seal provided between the generator-side partition and the generator. In accordance with this arrangement, it is possible to reliably block the flow of air from the chamber to be cooled having a high temperature to the air intake chambers having a low temperature on opposite sides of the chamber to be cooled, thus suppressing heat leakage from the chamber to be cooled to the air intake chambers on opposite sides thereof as well as imparting to the air intake chambers the function of suppressing noise leakage.
The engine generator may also include a base frame, an engine-side outside air inlet, and a generator-side outside air inlet. The base frame forms a part of the soundproofing case, the engine and the generator are disposed on the base frame, the engine-side and generator-side outside air inlets guide outside air to the engine-side and generator-side air intake chambers, respectively, and are provided in the base frame. In accordance with this arrangement, air can be introduced from the outside into the air intake chambers with a simple structure while minimizing leakage of intake noise to the outside.
The exhaust muffler may also be arranged in the chamber to be cooled above the generator and the exhaust vent provided in the cover part above the exhaust muffler. In accordance with this arrangement, the ventilation effect of natural convection within the chamber to be cooled is enhanced even after the engine generator is stopped. Moreover, the flow of air caused by natural convection is made to flow above the sections of the engine and the generator disposed within the chamber to be cooled, thus enhancing the cooling effect.
The above-described and other objects, characteristics and advantages of the present invention will become readily apparent from an explanation of a preferred embodiment that will be described in detail below by reference to the attached drawings.